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import os
# Define a context manager to suppress stdout and stderr.
class SuppressStdoutStderr(object):
'''
A context manager for doing a "deep suppression" of stdout and stderr in
Python, i.e. will suppress all print, even if the print originates in a
compiled C/Fortran sub-function.
This will not suppress raised exceptions, since exceptions are printed
to stderr just before a script exits, and after the context manager has
exited (at least, I think that is why it lets exceptions through).
'''
def __init__(self):
# Open a pair of null files
self.null_fds = [os.open(os.devnull,os.O_RDWR) for x in range(2)]
# Save the actual stdout (1) and stderr (2) file descriptors.
self.save_fds = [os.dup(1), os.dup(2)]
def __enter__(self):
# Assign the null pointers to stdout and stderr.
os.dup2(self.null_fds[0], 1)
os.dup2(self.null_fds[1], 2)
def __exit__(self, *_):
# Re-assign the real stdout/stderr back to (1) and (2)
os.dup2(self.save_fds[0], 1)
os.dup2(self.save_fds[1], 2)
# Close all file descriptors
for fd in self.null_fds + self.save_fds:
os.close(fd)
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